The invention relates to fastening apparatuses with fastening elements driven by a piston propelled in a cylinder of an internal combustion engine, forming, with a cylinder head, a combustion chamber wherein a mixing, draining and cooling fan is provided. Indeed, the fan first enables the flammable gas and air mix to be obtained; it also enables the combustion chamber to be drained from combustion residues; finally, the fan also enables all the members which may have been heated upon the shot to be cooled, specially the cylinder, the piston, the cylinder head and other elements making up the combustion chamber.
Until recently, the sum of the draining and cooling durations, after the shot, during which the fan is still rotatably driven, was determined upon the design of the apparatus and set in the factory.
Thermal facts were not taken into account.
The applicant has already sought to improve the cooling conditions of the fastening apparatuses introduced thereabove, by seeking to take advantage of the motor of the fan being connected to an electronic management module and to the supply battery for the apparatuses.
Thus, from the application FR 2,870,771, there is known an apparatus with fastening elements driven by a piston mounted within a cylinder of an internal combustion engine and forming, with an cylinder head, a combustion chamber wherein a gas-air mixing, draining and cooling fan is provided, being associated with a driving electric motor connected to an electronic management module and a supply battery, a thermistor being provided in the vicinity of the fan motor for transmitting a temperature information to the management module.
The management module which, advantageously, includes a processor, manages the temperature information provided by the thermistor for determining the operating duration of the fan after the shot as a function of this temperature, for example using a ventilation duration and temperature table.
The improvement provided in FR 2,870,771, with a thermistor subjected to the temperature of the chamber, is already very interesting. The applicant has however gone further by seeking to inject into the combustion chamber a gas mass better adapted to the air temperature of the chamber, and therefore adapted to any thermal condition of the apparatus.